hey, I found the dog didn't I? didn't take long.
Sometimes it's the brain-storming that helps those connections

who knows how my brain links things together

and I don't know where I remember seeing it from but I'd seen it before on that site because I remembered the cast iron link.
The Madonna? I've seen one in much clearer glass with swirly coloured bits in it quite like the glass of Della's dog, so that was my first thought - and nothing is known of Guy Underwood and Bermondsey really, so who's to know that he didn't make something similar in a poured mold type way I suppose was the way I was thinking. He also made some fish. So I suppose I made that link to the glass similarity and animals.
Then I thought it through and suddenly thought it might be very old and bingo.
I find brain-storming very beneficial in research, even if the thought is completely wrong, it often leads to the right connection

m